!7

cmodule FluidTextFileSpike > DynPrintLog {
  srecord Entry(S header, S text, SS params) {
    long targetIndex;
    S actualText() { ret unquote(text); }
  }
  
  switchable int maxRefLength = 8;

  long maxFileSize() {
    ret rangeOfNHexNumberWithNDigits(maxRefLength);
  }
  
  transient S demoContent = autoUnindent_mls([=[
    refs="at *", name="index" [[
      entry 1 at abc
      entry 2 at def
    ]]
    i=abc [[hello]]
    i=def [[world]]
  ]=]);

  start-thread {
    print(demoContent);
    Producer<S> p = javaTok_onReader(stringReader(demoContent));
    new StringBuilder buf;
    new L<Entry> entries;
    S t;
    p.next(); // skip initial white space
    while ((t = p.next()) != null) {
      if (isMLS(t)) {
        S header = getAndClearStringBuilder(buf);
        entries.add(new Entry(header, t, parseEqualsCommaProperties(header)));
        p.next(); // skip white space
      } else
        buf.append(t); // part of entry header
    }
    pnlStruct(entries);

    // make a map and pessimistically assign byte indices to all entries

    new Map<S, Entry> relocationMap;
    for (Entry e : entries)
      mapPut(relocationMap, e.params.get("i"), e);
    makeIndices(entries);
    print(+relocationMap);

    // rewrite references

    for (Entry e : entries)
      if (hasReferences(e))
        e.text = replaceRefs(e, r -> lookupInRelocationMap(relocationMap, r));

    // write out

    long idx = 0; // index into file
    for (Entry e : entries) {
      assertEquals(idx, e.targetIndex);
      e.params.put("i", renderReference(e.targetIndex));
      S line = entryToString(e, idx);
      print_noNewLine(line);
      idx += lUtf8(line);
    }
  }

  S lookupInRelocationMap(Map<S, Entry> relocationMap, S ref) {
    Entry e = relocationMap.get(ref);
    //print("lookupInRelocationMap: " + ref + " => " + e);
    ret e == null ? null : renderReference(e.targetIndex);
  }

  S renderReference(long idx) {
    ret takeLast(maxRefLength, longToHex(idx));
  }

  void makeIndices(L<Entry> entries) {
    long idx = 0; // index into file
    for (Entry e : entries) {
      e.targetIndex = idx;
      idx += pessimisticEntryLength(e);
    }
  }

  S entryToString(Entry e, long idx) {
    ret entryToString(e, renderReference(idx));
  }
  
  S entryToString(Entry e, S idx) {
    SS params = litorderedmap(
      i := idx,
      l := intToHex_flexLength(l(e.text)));
    mapPutAll_noOverwrite(params, e.params);
    ret renderEqualsCommaProperties(params) + " " + e.text + "\n";
  }  

  S dummyRef() {
    ret rep('0', maxRefLength);
  }

  bool hasReferences(Entry e) {
    ret eq(e.params.get("refs"), quote("at *"));
  }

  int pessimisticEntryLength(Entry e) {
    Entry e2 = e;
    if (hasReferences(e)) {
      e2 = cloneObject(e);
      e2.text = replaceRefs(e, r -> dummyRef());
    }      
    ret l(entryToString(e2, dummyRef()));
  }

  S replaceRefs(Entry e, IF1<S> f) {
    LS tok = javaTok(e.actualText());
    for (int i : jfindAll(tok, "at *")) {
      S x = f.get(tok.get(i+2));
      if (nempty(x))
        tok.set(i+2, x);
    }
    ret multiLineQuote(join(tok));
  }
}